[go: up one dir, main page]
More Web Proxy on the site http://driver.im/
Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Testing recovery using advice.jpg #83

Open
palmerc opened this issue Nov 29, 2022 · 4 comments
Open

Testing recovery using advice.jpg #83

palmerc opened this issue Nov 29, 2022 · 4 comments
Labels
documentation

Comments

@palmerc
Copy link
palmerc commented Nov 29, 2022

As an exercise in understanding how to work with known plaintext that is compressed I unzipped the zip file and did the following:

python3 ../tools/deflate.py < advice.jpg > advice.deflate
../bkcrack -C secrets.zip -c advice.jpg -p ./advice.deflate -t 12

Could not find the keys.

This suggests that the compression settings are wrong. I've tried changing the compression settings, but nothing seems to work. I think this would be a useful example for the tutorial
@kimci86
Copy link
Owner
kimci86 commented Nov 29, 2022

You are right, using the deflate python script (using zlib deflate compressor under the hood) does not generate correct compressed data for that example. I created the example secrets.zip archive using 7zip with compression level 9.
You can get the same compression with this command: 7z a -mx=9 plain.zip advice.jpg

That information could be a nice addition to the tutorial, thank you for the suggestion.
Let's keep this issue open to remind me to eventually add it.

@palmerc
Copy link
Author
palmerc commented Nov 29, 2022 •
edited
Loading

Tested and works!

palmerc@foxtrot example % 7z a -mx=9 plain.zip advice.jpg
palmerc@foxtrot example % ../bkcrack -C secrets.zip -c advice.jpg -P plain.zip -p advice.jpg 
bkcrack 1.5.0 - 2022-11-29
[19:56:51] Z reduction using 54681 bytes of known plaintext
16.0 % (8732 / 54681)
[19:56:51] Attack on 141 Z values at index 46518
Keys: c4490e28 b414a23d 91404b31
36.9 % (52 / 141)
[19:56:51] Keys
c4490e28 b414a23d 91404b31

@palmerc
Copy link
Author
palmerc commented Nov 29, 2022

Even with only 12 bytes of 'plain text' it results in victory.

palmerc@foxtrot example % ../bkcrack -C secrets.zip -c advice.jpg -P plain.zip -p advice.jpg -t 12 
bkcrack 1.5.0 - 2022-11-29
[20:05:02] Z reduction using 5 bytes of known plaintext
100.0 % (5 / 5)
[20:05:02] Attack on 1046104 Z values at index 6
Keys: c4490e28 b414a23d 91404b31
63.5 % (664022 / 1046104)
[20:13:02] Keys
c4490e28 b414a23d 91404b31

@palmerc
Copy link
Author
palmerc commented Nov 30, 2022

You can also leverage the fact that 7z can give you the CRC on a binary file. I saw a post that used this fact to find the released version of putty - this allowed them to find the original plaintext by downloading each one until they hit the one with a matching CRC. Then it becomes a matter of compression settings.

palmerc@foxtrot example % 7z h advice.jpg 

7-Zip [64] 17.04 : Copyright (c) 1999-2021 Igor Pavlov : 2017-08-28
p7zip Version 17.04 (locale=utf8,Utf16=on,HugeFiles=on,64 bits,10 CPUs LE)

Scanning
1 file, 54799 bytes (54 KiB)

CRC32             Size  Name
-------- -------------  ------------
7CA9F10A         54799  advice.jpg
-------- -------------  ------------
7CA9F10A         54799  

Size: 54799

CRC32  for data:              7CA9F10A

Everything is Ok

palmerc@foxtrot example % ../bkcrack -L secrets.zip 
bkcrack 1.5.0 - 2022-11-29
Archive: secrets.zip
Index Encryption Compression CRC32    Uncompressed  Packed size Name
----- ---------- ----------- -------- ------------ ------------ ----------------
    0 ZipCrypto  Deflate     7ca9f10a        54799        54700 advice.jpg
    1 ZipCrypto  Store       a99f1d0d         1265         1277 spiral.svg

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
documentation
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
2 participants
@palmerc @kimci86